Automatic telephone system.



C. S. W\NSTON. AUTOMATIC TELEPHONE SYSTEM.

APPLICATION HLED SEPT. 1?, X913- Patent-ed June 26, 1917.

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AUTOMATIC TELEPHONE SYSTEM. APPLlCATlON HLED SEPT. 11. 19l3- 1 ,23 1 3 1 9 Patented June 26, 1917..

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AUTOMATIC TELEPHONE SYSTEM. APPLICATION HLED SEPT. 17, 19l3,

Patented June 26,1917.

3 SHEETS-SHEET 3- Z/ Z/ 22221555: .752/222752'1' Q ffiaries 5D Z Q'ZZEZm.

v z q 1 nalis provided with ten sets of bank contacts 8 9 10.

Iii Fig. 2, I have illustrated the preferred mechanical arrangement of the line switch B, like parts being indicated by like reference characters \Nith the switch inits normal position, the cut-oil relay retaining pawl 11 engages the driving ratchet 12, while the line relay retaining pawl 13 is disengaged from said ratchet. Whena call is initlated, the line relay LR is energized followed by the energization of the cut-oil relay 'CO,

these relays remaining energized during the selecting operation of switch B whereb pawl 11 is disengaged from ratchet 12, whi e pawl 13 is in engagement withsaid ratchet. Upon the selection of an idle trunk, cutoff relay CO restores but the line relay remains energized until a disconnection is desired, at which time the line relay is deenergized and the cut-off relay energized so that both retaining pawls are disengaged from the ratchet 12 whereby the'wipers are permitted to restore to normal by spring tension.

Before proceeding with the description of the circuit arrangements of the selector and connector switches, I will describe briefly the preferred switch arrangement employed for these switches, this being illustrated in Fig. As already outlined, the directive switches which include the selectors and connector, are preferably of a two-dimension 100 point type, there being 100 sets of contacts arranged in groups of ten contact sets 14:, 15', 16 each, these contact sets being represented by a single element in the illustration as it is thought in this manner it will.

. be as easily understood and without complicating the illustration. A set of wipers 17, 18, 19 are also provided for cooperating with said. bankv contacts, said wipers being supported by a primary shaft PS which 15 adapted to be rotated in a primar direction by means of a primary magnet M and associated driving mcchanism'of a well-known type, to select a row or group of contacts. "Thereafter a secondary shaft SS is adapted to be moved downwardly by means of a secondary magnet SM and a well-known form of ratchet and pawl mechanism, thereby rotating the wipers in their secondary ad ust- .circuit with RV, but the relay RV will not.

1 travel of the wipers is illustrated by the dotted line in Fig. 3, the arrows thereon indicating the direction of travel of the wipers but the degree of primary travel of course depends upon the row selected. Now as to the restoration of the ofi-normal switches, upon the restoration of the wipers to the point 20 on the dotted lines, the switch PON is-restored and thereafter upon the wipers reachin their normal resting position the switch ON is restored.

It is thought that the above description of the switch mechanism is.sufiicient to give an understanding of the preferred mechanism employed but for a more complete under-. standing of this switch mechanism, reference may be had to an application of Wm. Kaisling for.automatic switches Serial No. 600,664, Patent No. 1,131,140.

Referring now to the circuit arrangement. of first selector C, a primary magnet PM is rovided as is also a secondary magnet S1 An impulse relay IR which is adapted to be controlled over the metallic circuit of the line for transmitting primary impulses, is also provided together with a slow acting secondary relay SR which is adapted to brin about a secondary circuit change to sett e secondary magnet SM in operation. The secondary selection of the switch is controlled by a test relay '1 and the release of the switch is controlled by a slowncting rcla RR which is adapted to be energized w'lien the impulse relay is initially energized, said release relay remaining cncrgizcd as long as the impulse relay is vibrated at a. prcdetermined rate. But upon a prolonged interru tion of the circuit of RR it. is adapte to retract its armature and thcrcby bring about the release of the switch. A rcversmg relay RV 'is also provided which relay has its winding included in circuit with relay T or other relays after each series of primary impulses are transmitted. This relay RY is of a comparatively low resistance while the relay '1 is of a comaratively high resistance so that the relay will attract its armature when included in I have found that a resistance of 100 ohms for the reversing relay and'a resistance of 1000 ohms for the test relay operate very well.

When a switch G is initially selected, the impulse relay IR is immediately energized over the callingline whereby both the slow acting relays RR and SR are also energized, both of said relays remaining energized during the rapid operations of IR in transmitting primary impulses. Upon cessation of such primary operations of IR, RR remains energized while IR is energized, but the secondary relay SR, due to a prolonged interruption of its energizing circuit retracts its relay also.

armature and therefore establishes an energizing circuit for the test relay T throu h the winding of the reversing relay RV. 1- though the test relay T attracts its armature, relay RV does not receive sufficient current to attract its armature and therefore u on energization of T the secondary magnet CM advances the wipers until an idle trunk is engaged.

, Now, as to the second selectors D, these are also provided with primary magnet PM, a secondary magnet SM, test relay T and release relay RR the primary im pulses for this switch. being transmitted from the impulse relay IRot the first selector, which relay IR serves as a repeating switch D, its test relay T is connected in circuit with the reversing relay RV of first selector G to brin about the secondar o eration of switch. D, but the'relay T being of a high resistance like the relay T, relay RV does not attract its armature although I te seconda y o e Rel'crrin;

l relay T'- does and brings about the ration of switch 1).

ow to the connector switch E,

a release relay/RR is provided which is :ulaptedto be energized upon selection of its switch, a second release relay RR" also he- 3 ingf'proridcd for the purpose of connecting the secondary magnet SM in a release cir- MCI t when'ja relmise of switch E is desired.

'aiidfimondary magnets PM, SM, ti ely are also pr'ovuled as is also r relay SW which is adapted to be "courier ed in circuit with the reversing relay RV rcs'l'ion'slvefto the secondary circuit I, change ."tollowing the" primal "5o I v operation of the connector. The sairl'rel: SV is also of a high rc;'sl'ancc.- so that a though it will attract its armature, it will not permit sufficient current amine through thercvcrsing f reluy to Turing about the (nicratio'n'thereof. Relay HWus adapted WlHTtflHQI'glZGfl, to

disconnectthe primary magnet PM and conncrtthe secondary magnet SM in circult with the prunary conductorso as to be operated by thcjast set of primary impulses.

Following the transmission of the last series of primary impulses, the reversing relay RV is coniwctwl in circuit with the second switching rcla y SW which also of a high resistance so that it will operate without pcrmitting the operation of RV, this operation- At'ter the primary operation of of SW being eflective to connect the line test relay LT in circuit with the called line. A supplementary relay His also provided which is energized or denergized according to the condition of LT. If the line tested is idle the interrupter relay I is energized to alternately connect ringing current or the control relay GR in bridge of the called line. When a response is secured from-the called substation, control relay GR, circuit closing relay CL anddisconnect relay DR are energized. This connects the lower Winding of the control relay GR in circuit with the reversing relay RV, but in this instance due to the low resistance of this lower winding of OR, the reversing relay is energized sutliciently to attract its armature and reverse the current over the calling line to operate the electromagnetic device 0.

Should the called line tested be busy, then the slow acting busy relay BR which had been energized upon the initial step of switch E, retracts its armature and thus connects the busy backBB in circuit with the calling line to notify the calling substation thot the desired line is busy. 1

The called line L and its switch B are of course similar to the calling line, the like parts being indicated by like reference characters except for the addition of the suffix prime.

Operation.

line conductor 4, through the substation A including the winding of polarized mag net 0, conductor 3, normal contact iii, primary conductor and wiper 6 to ground. Relay LR therefore energizes causing check pawl 13 to engage the driving ratchet 12 while the closing of alternate contact 27 places ground upon the test terminal 28' which appears at certain connectors together with the associated terminals 29, 30. Also upon the closing oi alternate contact 27 a circuit is established through normal contact-0N for cutmtl' relay (10 causing its operation, whereby the circuit lfor motor magnet M is established from 'ground through alternate contacts 252, 33,

and the winding of M to the alternate current generator. Responsive to the first current impulse through. M, wipers 5, (i, 7, are

' their test contact 8.

LE to battery, and also through contact 31 e and winding of CO to battery maintaining these two relays energized. Therefore the motor magnet M advances the wipers another step andin fact continues such advancement until the test Wiper 5 reaches an idle'set of contacts Which we will assume is the third contact set leading to switch 1 C. The test contact 8 of the idle set having no ground or busy potential connected there to, the circuit for CO and LR is interrupt-- ed and CO being a quick acting relay immediately retracts its armature nterrupting the circuit of M and rendering the wipers inert. Relay LR is a sluggish acting relay and therefore maintains its armature attracted until a locking circuit is provided from alternate contact 35 of IR which is brought about as follows:

Upon the said deiuiergization of CO following the selection of idle first selector C, the impulse relay IR is connected in bridge of the calling line establishing an energizing circuit therefor which may be traced from ground through the left winding thereof, normal contact- 36, back over the primary conductor, contact 9 and wiper 6, nor mal contact 20. through substation A and its polarized magnet 0, conductor i, normal contact 25, wiper 7 and contact 10, normal contact 37 and the right end winding of IR- i'o lmttery. Relay IR therefore attracts its armature closing alternate content 35 and connecting ground over conductors 3?), to test contact 8 and wiper fl. alternate conact 31 and the winding of LR to battery maintaining LR energized. This ground connection to contact 8 also serves as a busy potential and thusprerents other line switches from selecting the trunk leading from the multiply connected contacts 8. Also responsive to the operation oi III, a circuit for re lease relay HR is established traced from battery through the winding of RR, alternate contact 40 to ground at normal contact 41, thus energizing I- R whereby its alternate contact 4-2 is closed to serve as a holding circuit for RR and maintain alternate coirtact 40 grounded after switch C has stepped off-normal and normal contact 41 is inter rupted.

Upon energization of RR, a circuit for the secondary relay SR also established traced from battery through the winding of SR, normal contact 43, alternate contact 44 to ground at alternate contact 40 thus energizing SR to interrupt it normal conthat upon the first tact 45 and. to prevent a premature operation of the test relay T.

Although current flows through magnet O first from battery then LR and then through IR, this flow is not in a direction to effectively operate magnet O.

The switch C is now in condition to receive the first set of primary impulses this being brought about by the operation of calling device 2 to interrupt contacts 1 two times, corresponding to the first digit of the called substation. Contacts 1 being included in the energizing circuit of IR, the two interruptions thereof are effective to cause two operations of the primary or impulse relay IR whereby two primary 1mpulses are transmitted through primary magnet PM traced from ground at normal contact 40 upon each operation of IR, alternate. contact 46, normal contact 47 of SON, and the winding of PM to battery. The ensuing two operations of PM are effective to advance Wipers 17, 18, 19 two primary steps to select the second row of contact sets 14, 15, 16, which row leads to second selectors in the 2000 group. It will be noted rimary step of switch C, the initial energizing circuit of SR is interrupted at normal contact 43 of PON, but each time relay IR is denergized, a holding circuit for SR is established from normal contact 35, alternate contact 43 and the winding of SR so-that relay SR which is a sluggish acting relay maintains its armature attracted during the primary operations of IR.

Upon cessation of the first series of primary operations of IR, said relay is maintained energized through the calling line un til the next operation of the calling device 2. this period of energization being sufficient to permit of the restoration of SR when its circuit is interru )ted at normal contact 35. Relay SR there ore closes its normal contact 15 to bring about the secondary operation of the switch due to the establishment marginal difference between the operationsof RV and T, sufficient currentflows to operate relay T but not relay RV andthe'refore upon the closing of alternate contact 53, a circuit for secondary magnet SM is established whereby wipers 17, 18, 19 are advunccd in their secondary adjustment to engage the first set of contacts 14, 15, 16 V of the selected row.

Upon the first secondary step of the switch, the initial energizing circuit for T is interrupted at normal contact 50, but, assuming the first contact set engaged leads normal contact 89, and the winding of BB to battery, said relay BR thereby energizing but without any immediate effect upon the circuit.

Following the said four primary operations of IR, the associated secondary relay SR deenergizes as before whereby a sec0ndary circuit change is brought about to effect the energization of switching relay SW of connector E the energizing circuit for SW being established over a path traced from ground through the winding of RV, normal contacts 52, 15, over the secondary conductor to the secondary conductor of connector E, branch conductor 90, alternate contact 91, normal contacts 92, 93, and the winding of SW to battery whereby relay SW energizes and establishes a locking. circuit for itself through alternate contact 94, normal contacts 95, 76, to grounded test conductor 75. The operation of SW is effective to disconnect PM and connect SM to the primary conductor of switch E due to the operation of alternate contact 78.

The subscriber at substation A now operates the calling device 2 to effect three operations of the impulse relay IR, corresponding to the last digit of the number of the called substation. Responsive to the three operations of IR, the associated secondary relay SR is energized and maintained energized as before and three primary' impulses are transmitted from the grounded normal. contact 40 and over the primary conductor toconnector E, branch conductor 77, alternate contact 78, normal contact 96, winding of SM to battery at normal contact 97. These-three primary impuls ause three operations ofthe secondary in gnet SM wherebythe wipers 80, 81, 82, are advanced three secondary steps to engage the third set of contacts 83, 84,

85, which contacts are the terminals of the Wanted line;

Followingthe last three operations of IR, relay -SR deinergizes as before whereby a secondary impu se is transmitted from ground through RV and over these'condary conductor to connector E, branch conductor 90, alternate contacts 91, 92, normal contact 98 and the winding of SW to battery, This circuit. permits the operation of relay SW but sufficient current does not flow to operate RV,the1,'efore SW" operates to attract its armature ai'id interrupts its normal contact 95, restoring the other switching relay SW. At

the same time alternate contact 99 of SW is closed whereby a locking circuit for SW? is established over conductors 88, 87 87 to' ground at normal contact 86. Also, re sponsive to the operation of SW its nor,

mal contact 89 isinterrupted to' open the energizing. circuit for relay but said relay, being a slow acting relay is able to maintain its armature momentarily attract- .I ,th.erefore the energization of vented until .a path for directcurrent is -pro .vided 'wheuthe.receiver at substation A ised, or with the called line idle, until a substitute holding circuit therefore is provided as will be described. Responsive to the closing of alternate contact 89 of SW, line test relay LT is connected in circuit with the test contact 83. of the called line. From this point on the operation ofconnector Edif ers depending upon whether the line con nected with is in an idle or 'busy condition.

Uallecl line idle.

.Relay LT therefore energizes causing the immediate energization of its supplementary relay H whereby alternate contact 103 of H is closed to establish a holding circuit for relay BR before it-has had time to retract its armature and thereby preventing the relay BR from connecting busy back BB with the calling line. Also responsive to the operation ofLT, its alternate contacts 105, 106, 107, are closed short-circuiting the winding 101 but'connecting the hold-- I ing winding 108 through alternate'contacts 105 and 107, to alternate contacts 102, 89, conductors 88, 87, 87 to ground at 86,'this ground connection. also extending through alternate contact 106 and conductor 109 through the winding of the cut-off relay CO.

to battery, also maintaining this relay energized. J

The closing of alternate contact 101 of LT, also establishes a circuit for interrupter relay I through normal contact 110 and the interrupter 111", sothat relay 1' i's'alternately energized and deenergized operating its contacts 112, 113. The closure of alternate contacts 112, 113 connects the ringing gen erator G in bridge of the calledline so as to ring the call bell at substation A while upon each closure of normal. contacts -112,

.113, the control relay GR is connected inbridge of the called line through alternate contacts 114, 115, of relay H. As long as the receiver is upon the switch-hook at the called substation, no direct current is permitted to flow through said substation on account ,of the interposed-condenser and GR is 'pref-The subscriber .at substation A now re- I novesghis -rec'ei ver from' its switch-hook in responseto the-signal, thus providing an contact 118 of CR, a circuit for closing re lay CL is established whereby said relay energizes closing its alternate contacts 119,

120 and thereby establishing a continuity.

of the talking conductors between the two substations.

Upon energization of CL its alternate contact 1.21 is closed establishing an energizing circuit for disconnect relay DR whereby normal contact 110 of DR- is interrupted relulering interrupter relay I inert.

The direction of current flow over the called line and through the polarized magnet O of its substation, is such that the armature of O is attracted toward the left so that no efiecti've operation of the register occurs As already referred to,upon a response be ing secured; from the called substation, the direction of current flow over the calling line is reversed, this being brought about by the inclusion of the reversing relay RV in circuit with the lower winding of CR at the time relay CL energizes. This circuit may be traced from ground through the winding of RV, normal contact 52, over the secondary conductor to connector E, alternate contact 120 of CL, conductor 116, normal contact 113, alternate contact 115, and the lower winding of GR to battery. This lower Winding of OR of alow enough resistance to ermit-sufiicient current to flow through RV to cause the attraction of its armature so that relay RV operates establishing a locking circuit for itself through contacts 52, 123, alternate -"contact lit l, resistance 125 to battery. Also responsi to the operation of RV, its alternate contacts 36, 37 are closed wherebythe connection from. batter,

through IE to the calling line is reverse thus causing the operation-of the polarized magnet O at the calling substation. It will be noted that relay RV is now locked up through RR, and due to the-stact that RR is maintained energized by a control over the calling line, it will be apparent that this reverse flow is maintained until a release of thecormection is brought about, so that it is impossible to effect more than one operation of the magnet for each connection.

Theconnection between calling and called substations has thus been established, the

talking circuit being traced over the heavily marked conductors, talking battery being supplied to the calling the windings of relay R while talking current is supplied to the called substation throu h the windings oi control relay CR. lnter erence between these battery supplies is prevented by the interposed condensers 127, 128, at first selector C, thus also permitsubstation threw ting of separate control of tb rel'ys in the 1 two ends of the talking circuit.

It is of course to be understood that the plurality f of batteries shown may b one and thesame.

Release.

Now as to the rajease of the apparatus employed in a connection, I have preferably arranged the present embodiment of my in-- vention so that the control of the release of switches B, and D, of an established connection is with the calling substation, while the release of the connector E is under thecontrol of the called substation.

Assuming now that the subscriber at the calling substation is the first to replace his receiver upon its switch-hook, the circuit for.

ing the holding circuit for RV, while the 1 closing of normal contact 55 on HR establishes an energizing"circuit for relay T which maybe traced from battery through" the. winding of T, normal contact 55, alter nate contact 43 and normal contact 35 to ground. through alternate contact 43 incidentally causes the energization of SR. Relay T This ground connection from 35* thus is energized to interrupt its contacts 57, 1 58 before the..1'eve1.'sing relay can again be energized over the secondary conductor, wh le the closing of alternate contact 53 of T establishes anenergizing circuit for SM whereby wipers 17, 18, 19 are advanced be yond the last contact of the selected row' from which point they are automatically restored to normal over the path indicated by the dotted line in Fig. 3, as already described. Upon interruption of alternate contact 43 of PON, upon the" restoration of switch C, the circuit for relays T, and SR is Y interrupted allowing the restoration of these relays and thus switch (J is at normal Upon interruption of alternate contact 41.

of PON in the restoration of switch C, the

holding circuit for line relay LR is interrupted, permitting the restoration of LR whereby the closing of its normal contact 27 establishesfan operating circuit for CO through alternate conta t ()N. Thus relay, LR being deehergized-t=.;id-relay (1O enerboth-the check pawls 11, 13 are out of engagement with the ratchet 12 and therefore the wipers are permitted to restore to normal interrupting alternate contact ON whereby relay CO is again at normal and switch B is now available for use in extendingIother calls.

ow as to the restoration of second selector D, it will be remembered that its release relay RR was maintained energized through its alternate contact 61, test con ductor 59 and back to ground at normal contact 54 of relay T, switch C. Therefore when relay T energizes in the restoration of switch C, this holding circuit for BB is interrupted at normal contact 54 allowing the restoration of RR: A release circuit for switch D is thereby established traced from ground at alternate contact 129 of PON, switch D, normal contact 130, and the winding of T to battery. Relay T is thus energized closing its alternate contact 71 and thereby establishing an operating circuit for SM whereby wipers 63, 64, 65 are advanced to bring about their restoration to normal in a manner as previously described. It will be noted that during the restoration of switch D, a ground or busy potential is maintained upon the test conductor 59, its multiply connected test contacts 14:, from ground at normal contact 131 of RR through alternate contact 60. Upon restoration of switch D, and the interruptii ig of alternate contact 129 on PON the circuit for T is interrupted causing its restoration and thereby rendering SML inert. for use in establishing other connections.

Be ferring now to jthe release of ,connector E; when the receiver is replaced upon its switch=hook at's ubstation A the, circuit for relay 'CR is of course interrupted causing the restoration of CRand the interruption of its alternate contact 118 which causes the denergization of relay CL. At the same time alternate contact 117 of OR is interrupted thus interrupting the holding circuit of relay BB whereby it restores to normal closing its normal contact 132 and establishing an enel gizing circuit for BB, from ground at alternate contact 86 of PON. The energization of RR -is effective to bring about the release "of switch E through the operation of SM by the closing of alternate contacts 96, 97. l

Also responsive to the restoration of BB and due tq the interruption ofits alternate contact 10% the holding circuit for relays LT and C6 is interrupted, as it will be remember-ed that these two relays were maintained energized over a-holding circuit including this alternate contact 102, over a 2 reviously described path to ground at alornate contact 86 o PON". Relays LT and CO therefore restore to normal, the

Switch ,ID is now available 5 stored. Switch D being at normal is again available for use in establishing other connections.

Called line busy.

Having described the operation of the system when connection is established to an idle called line, the operation thereof will now be described when connection 1s made with a busy called line. As already pointed out the operation of the apparatus in the course of establishing a connection is the same up to the transmission ofthe final secondary impulse and the consequent energization of SW, whether connection is made to an idle or a busy line.

It will be remembered that up to and including the transmission of this last secondary impulse, relays RR SW and BE are energized, relay SW having been energized by the last secondary circuit change and by the closing of its alternate contact 8'.) has connected the lower winding of LT in circuit with the test contact 83 of the called line. Assuming that the called line is busy, its test terminal 83 will have a ground or busy potential connected thereto either through alternate contact 27, if the line be calling or from a connector switch it the line be a called line. Therefore no energizing circuit is established for the linetest relay LT because both terminals of its winding 101 are connected to ground potential. Therefore its supplementary rela H does not energize and "of course no ho ding circuit for busy relay BRisestablished. There fore said relay BR restores interrupting its alternate contact 100 to open the circuit of the test wiper 80, while the closing of itsv the receiver of its substation, returning over the secondary conductor to switch C and over conductor 137, normal contact 37, and the winding of IR to battery and ground.

The calling subscriber in response to this signal will of course replace his receiver and D, are restored to normal. in a manner as previously described, but in this instance the connectorswitch E is also restored.

It will be remembered that due to the connection having been established with a busy line, relay CR did not energize to close its alternate contact 117 and therefore no addi tional holding circuit for RR was" pro vided whereby said relay RR was maintained energized back through the grounded test conductor 75. Therefore when ground was removed from this conductor 7 5, due to the interruption of normal contact 74 of relay T at second selector D, release relay RR restores tonormal closing its normal contact 132 whereby an energizing circuit for BR is established in a manner as before described and, thus bringing about the operation of SM and the restoration of connector E.

It will be noted that when connection is made with a busy called line, thereversing relay RV doesnot operate and therefore no reversal of current flow over the calling line is efiected, in which case the magnet O at the calling substation does not effectively operate.

In illustratin my invention I have shown a plurality of batteries, this method being followed for the sake of simplification but I contemplate using one common source of current; Also it is to be understoodthat a single alternating current generator for driving the operating magnets is the preferred arrangement. Although I have embodied my invention in a straight automatic telephone system, I contemplate applying it in other ways and therefore I do not desire to be limited'to the exact structure as shown and described.

Having described my invention what I claim as new and desire to secure by Letters Patent is:

1. A telephone system comprising a calling telephone line, a source of current connected to said line, automatic switches for extending the circuit of said line, a called line, means for producing im nlses for controlling the operation of sai switches for extending the circuit of' the calling to the called line, a"margina1 reversing relay included in direct circuit of certain of said impulses,means to prevent efi'ective operation of said relay'when so included, an electromagnet, and means effective u on response of the substationof the cal ed line for operating said reversing relay to reverse the current connections to the calling line to operate said electromagnet,

-nectcd to said line and \flowin 2. A telephone system comprising a calling telephone line, a source of current connected to said line, automatic switchesfor extending the circuit of said line, a called line, means for producing impulses for controlling the operation of said switches. in extending the circuit of the calling to the called line, a reversing relay included in circuit of certain of said impulses, said circuit including suflicient resistance to prevent operation of said relay, mechanism, and means controlled over the called line for causing the operation of said reversing relay to reverse the current connection to the calling line to operate said mechanism.

3. A telephone system comprising a calling telephone line, a source of current connected to said line and flowing thereover, automatic switches for extending the circuit of said line, a called line, means for..

for causing the operation of said reversingto reverse the current flow over the rela calling line to operate said electromagnetic means.

4, A telephone system comprising a calling telephone line, a source of current connected to said line, automatic switches for extending the circuit of said line, a called line, means for producing primary and secondary impulses for controlling the operation of said switches for extendin the circuit of the calling to the called line, a reversing relay included in circuit of each secondary impulse, said circuit including sufficient resistance to prevent efl'ective operation of the said reversing relay, an electromagnet, and means eifective upon response from the substation of the called line for operating said reversing relay to reverse the current connection to-the calling line to efiectively operate said electromagnet.

5. A telephone system comprising a calling telephone line,fa" source of current conthereover, automatic switches for extending the circuit of said line, a called line, means for,

netic means and means for causing the oper-- ation of said reversing relay to reverse the,

current flow over the calling lineupoi'i w line to operate said electromagnetic means.

spouse from the substation of the called I operation of said switches for interconnecting said lines, a marginal reversing relay included in direct circult of each secondary I impulse, means to prevent 'efiective operation of said reversing relay when so included, electromagnetic mechanism, and means controlled over the called line for causing the operation of said reversin relay to reverse the current connections to t e calling line to operate said electromagnetic mechanism; 4

7. A telephone system comprising a calling telephone line, a source of current connected to said line and flowing thereover, an

im ulse'relay included in saidconnection, a ca] ed line, automatic switches adapted for interconnecting said lines, a calling device at the substation of the calling line for operating said impulse relay, means for producing primary and secondary impulsesres onslve to said operation of the impulse re ay for controlling the operation of said switches for interconnecting said lines, said primary impulses bcing equal in number to ,the number.-

of impulses transmitted by said calling device, a reversing-relay included in circuit ofv each secondaryimpulse, means to prevent effective operation of said reversing relay when so included, an electromagnet, and means effective upon response of the substation. of the called. line for operating said,

reversing relay to reverse the current flow over the calling lineto operate said electromagnet.

8. A telephone system comprising a call ing telephone line, a source of current connected to said line, a called line, automatic switches adapted for interconnecting said lines, means for producing primary'and secondary impulses for controllingjhe operation of said switches for interconnecting said lines. second ary-impulse perated control relays for said switches, a reversing relay, means for including said rcversingrelay and one of said control relays in circuit of ach of said. secondary impulses, means to prevent cli'ective operation of said; reversing relay when so included, mechanism, and means conl'mllcd over the called line for 0pcrating said reversing relay to'rcvcrsethe current connections to the calling line to cll'crt said mechanism. I v

f). A telephone comprising telephone lines, selector and connector switches for interconnecting said lines, reversing relays for the selectors, control relays for the for interconnecting said lines, reversing relays for the selectors, control relays for the connectors for furnishing transmitter currents to the called lines, circuit connections effective upon a response from a called sub.- station for including the windings of the reversing and control relays in circuit whereby said reversing relay is operated to reverse the battery connection to the calling line to operate an electromagnet, and means for disconnecting the reversing relay from the control relay upon its operation and placing said reversing relay under control of the calling substation. l

11. A telephone system comprising telephone lincs, automatic switches for interconnecting a calling and called line, means for producing impulses for operating said switches to effect such connection, a single wound reversing relay included in vcircuit of certain of said impulses, means to prevent eli'ective operation of said relay when so included, electromagnetically controlled mechanism, 'means active upon response from the called substation foroperating said reversing relay to reverse the battery connections to the calling line to operate said mechanism,- and circuit connections for placing said. reversing relay when so operated under control of the calling line.

12. A telephone system comprising telephone lines, automatic switches for inter! connecting a calling and called line, means for producing primary and secondary impulses for operating said switches. to eiTect such connection, a reversing relay included in circuit of each secondary impulse, an electromagnet, means to, prevent effective operation of said relay when so included, means -act1ve upon response from the called subs pulses for operating said switchesto effect such connection, secondary-impulse-operated 'mechanism means'controlleal.ovcr the called line for operating said reversing relay to reverse. the battery (.(IUIIPL'tlOIIS to the call ing line to cause an operation oi. said mechanism, and circuit connections for placing said reversingrclay when so operated un-. der control of the calling line 14. A telephone system comprising a calling and a called telephone line, automatic means for connecting said lines. means lorated at the calling substation for producing impulses for operating said, automatic means to ellect such connection, a reversing relay included in the direct circuit other" tain of said impulses, means to prevent the operation of the said relay when so included, elertromaguetieally controlled means, and means operated upon response From the said called line for operating said reversing relay to reverse the battery connections to the calling line to operate said clectromagnetr cally controlled means.

15. A telephone system comprising a calling and a called suhscribefis line, automatic switches for connecting said calling and said called line, means for interrupting the calling suhscribens line circuit for operat ing said switches to effect such connection, a reversing relay provided with a Winding included in the direct path of certain of said impulses, an electromagnet, and means effective upon response from the said called line for effectively energizing said reversing relay to reverse the battery connection. to the said calling line to operate said electromagnet.

Signed llV me at Chicago, county of Cook and State of Illinois. in the presence of two witnesses.

CHARLES S. WINSTON, \Vituesses:

GEORGE E. MUELLER, M. R. Rocnronn. 

